The present invention relates to a self-adhesive disposable body warmer, and more particularly to a self-adhesive disposable body warmer comprising iron powder as a main ingredient, which can set up and maintain a stable attachment, can keep a stable heat distribution state and further can be comfortably used in direct contact with or in close vicinity to the skin.
A disposable body warmer comprises an air-permeable bag and, accommodated therein, a mixture of metal powder such as iron powder available at a relatively low cost with assistants such as water, activated carbon, wood flour and salt and utilizes an exothermic reaction caused by supplying oxygen (air) thereto. It can be easily used by merely opening a wrapped, hermetically sealed bag, and occupies a major proportion of the body warmers in these days.
However, the above-described disposable body warmer requires the use of an attaching means in order to attach the body warmer to the human body. More precisely, the disposable body warmer is not in a form to be attached to the human body without being put in receptacle of an attaching band or the like, or placed in a pocket provided in underwear. In other words, although the disposable body warmer per se is inexpensive, the attaching means is considerably expensive and the attachment of the body warmer to the attaching means and removal thereof from this means are complicated. Further, even when the body warmer is put in such an attaching means or a pocket and attached to the human body, the position of attachment is limited, which often makes it impossible to attach the disposable body warmer properly to that part of the body where a thermal effect is most required.
As an expedient for eliminating the disadvantage of the conventional ordinary disposable body warmer, a self-adhesive heat generating bag has been proposed in Japanese Utility Model Publication (Y2) No. 34735/1981. This bag comprises a heat generating agent capable of generating heat upon being exposed to oxygen and placed in a flat heat generating bag having one surface permeable to oxygen with the other surface being provided with a nontransferable self-adhesive layer all over the surface or in a pattern form. This bag can be substantially properly applied to any site of the human body or the like and can be applied without use any expensive and special attaching means or pocket.
Although the nontransferable disposable body warmer may be thought to have above-described advantage, studies on the utility of this warmer conducted by the present inventor has revealed that such a body warmer generally stands substantially perpendicular or at a slant at least when applied to the human body and that in order to attain substantially uniform heat generation and heat quantity, the heat generating agent placed in the bag should be basically of a flat form and cannot be packed densely like, e.g., a sausage at a even when the peripheral portion is of a thin layer form. That is, the heat generating agent should be packed in a flat form while leaving a considerable space, which inevitably brings about uneven distribution or agglomeration of this agent in the bag when the body warmer is applied to the human body or the like. The uneven distribution, in turn makes the heat generation of the agent in the bag and the temperature distribution accompanying the heat generation uneven, and the agglomeration results in an unpleasantness to the user and further disturbs the state of heat generation.
Specifically, in one part of the heat generating agent, heat generation begins and is completed in an early stage, while in the other part thereof, remarkable heat generation occurs, thus causing skin burns or the like. The agglomerated heat generating agent deteriorates the touch, particularly results in an unpleasantness in a state when directly applied to the skin or applied to the skin through underwear, and remarkably disturbs the state of heat generation because the amount of supply of oxygen is lowered.